1. Field of the Invention
The present invention relates to a containment assembly (e.g., a down flow containment assembly) comprising a barrier means at least a first part of which is composed of flexible material, and to the barrier means itself.
2. Description of the Related Art
A conventional containment assembly comprises a powder handling booth of sufficient size to admit an operator for the purposes of handling (for example) pharmaceuticals or chemicals in a processing zone. The air quality in and around the processing zone may be controlled using forced ventilation. One category of forced ventilation is “down flow” in which surrounding air is pushed downwardly to entrain airborne particles to a level below the processing zone (e.g., to a level below the typical operator's breathing zone). For down flow containment, exhaust is usually carried out at low level relative to the source of particles. Current Good Manufacturing Practices exercised within the pharmaceutical manufacturing industry demand good containment performance and acceptable operator exposure levels.
A traditional down flow containment assembly is illustrated schematically in FIG. 1a (with air flow denoted A) for the purposes of (for example) handling a pharmaceutical powder within a powder drum 3. An operator 2 is subjected to exposure levels in the operator breathing zone 1 typically in the range 150 to 1000 μg/m3 (and possibly higher). In order to improve containment and to reduce exposure of operator 2 to airborne powder in the operator breathing zone 1, it has been known since about 1990 to isolate the operator's position by fitting a work station 4 into the down flow containment assembly (see FIG. 1b). The work station 4 typically reduces operator exposure levels to about 50 μg/m3. In a more recent development (see FIG. 1c), a transparent rigid screen 6 of a “salad bar” type has been found to improve exposure levels in the operator breathing zone 1 to about 10 μg/m3. The salad bar screen 6 allows the operator 2 to manipulate the powder through a gap between the work station 4 and the salad bar screen 6.
Notwithstanding these significant improvements, the pharmaceutical industry is striving for the effectiveness of a down flow containment assembly to be improved so that the exposure level in the operator breathing zone is less than 10 μg/m3. Moreover, with a conventional down flow assembly, there remains a significant risk of high localized contamination of (for example) the operator's hands or clothing which is quite unacceptable for handling pharmaceuticals or chemicals. Added to this, the work station and work station/salad bar developments restrict access to (and maneuverability in) the processing zone and are particularly prohibitive to unusually short or tall operators.
Objects of the Invention
The present invention seeks to improve operator exposure levels in a containment assembly (e.g., a down flow containment assembly) by providing a barrier means between the processing zone and the operator breathing zone. This is achieved without hindering the access to (or the maneuverability in) the processing zone of an operator of any height.